style.css

*{
    margin: 0;
    padding: 0;
}

.container{
    background-image: linear-gradient(to top, #9FA5D5 0%, #E8F5C8 100%);
    background-repeat: no-repeat;
    height:100vh ;
    font-family: Arial, Helvetica, sans-serif;
    text-align: center;
}

.calculadora{
    position: absolute;
    background-color: #00000070;
    top: 50%;
    left: 50%;
    transform: translate(-50% , -50%);
    border-radius: 10px;
    padding: 15px;
}

.calculadora h1{
    color: white;
}

#resultado{
    width: 223px;
    height: 30px;
    background-color: white;
    margin: 5px;
    font-size: 25px;
    color: black;
    text-align: right;
    overflow-x: auto;
    overflow-y: hidden;
}

button{
    width: 50px;
    height: 50px;
    font-size: 25px;
    cursor: pointer;
    user-select: none;
    background-color: #313131;
    border: none;
    color: white;
    margin: 3px;
}

button:hover{
    background-color: black;
}

footer{
    margin-top: 10px;
    font-weight: bold;
    font-size: 12px;
}

::-webkit-scrollbar{
    height: 4px;
}
::-webkit-scrollbar-track{
    background-color: grey;
}

::-webkit-scrollbar-thumb{
    background-color:#b490ca ;
}